boostorg · apolukhin · May 24, 2026 · Apr 13, 2026 · Apr 13, 2026 · Apr 18, 2026
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -105,6 +105,25 @@ jobs:
           ./b2 -d0 headers
           ./b2 -j4 variant=debug tools/inspect
 
+      - name: Run modules tests
+        if: ${{matrix.toolset == 'clang-19'}}
+        run: |
+          cd ../boost-root/libs/$LIBRARY
+          cmake -S test/cmake_subdir_test -B __build \
+            -GNinja \
+            -DBUILD_TESTING=1 \
+            -DBOOST_DLL_USE_STD_FS=1 \
+            -DBOOST_USE_MODULES=1 \
+            -DCMAKE_CXX_COMPILER=${{matrix.compiler}} \
+            -DCMAKE_CXX_FLAGS="-stdlib=libc++"  \
+            -DCMAKE_CXX_STANDARD=23 \
+            -DCMAKE_CXX_MODULE_STD=ON \
+            -DCMAKE_EXPERIMENTAL_CXX_IMPORT_STD=0e5b6991-d74f-4b3d-a41c-cf096e0b2508
+
+          cmake --build __build
+          ctest --test-dir __build --output-on-failure --no-tests=error -VV
+          rm -rf __build
+
       - name: Run modules tests without 'import std;'
         if: ${{matrix.toolset == 'clang-19'}}
         run: |

diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -54,7 +54,18 @@ target_link_libraries(boost_dll_boost_fs
 if (BOOST_USE_MODULES)
   add_library(boost_dll)
   target_compile_definitions(boost_dll PUBLIC BOOST_USE_MODULES)
-  target_compile_features(boost_dll PUBLIC cxx_std_20)
+
+  get_property(__standard TARGET boost_dll PROPERTY CXX_STANDARD)
+  if (__standard IN_LIST CMAKE_CXX_COMPILER_IMPORT_STD AND CMAKE_CXX_MODULE_STD)
+    target_compile_features(boost_dll PUBLIC cxx_std_23)
+    target_compile_definitions(boost_dll PRIVATE BOOST_DLL_USE_STD_MODULE)
+    message(STATUS "Using `import std;`")
+  else()
+    target_compile_features(boost_dll PUBLIC cxx_std_20)
+    message(STATUS "`import std;` is not available")
+  endif()
+  unset(__standard)
+
   target_sources(boost_dll
     PUBLIC
       FILE_SET CXX_MODULES

diff --git a/include/boost/dll/config.hpp b/include/boost/dll/config.hpp
@@ -47,8 +47,10 @@ using system_error = std::conditional_t<BOOST_DLL_USE_STD_FS, std::system_error,
 #ifdef BOOST_DLL_USE_STD_FS
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <filesystem>
 #include <system_error>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 namespace boost { namespace dll { namespace fs {
@@ -94,7 +96,9 @@ namespace boost { namespace dll { namespace detail {
 #else  // BOOST_DLL_USE_STD_FS
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <memory>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 namespace boost { namespace dll { namespace detail {

diff --git a/include/boost/dll/detail/aggressive_ptr_cast.hpp b/include/boost/dll/detail/aggressive_ptr_cast.hpp
@@ -14,9 +14,11 @@
 #endif
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <cstring>              // std::memcpy
 #include <memory>
 #include <type_traits>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 #if defined(__GNUC__) && defined(__GNUC_MINOR__) && (__GNUC__ * 100 + __GNUC_MINOR__ > 301)

diff --git a/include/boost/dll/detail/demangling/demangle_symbol.hpp b/include/boost/dll/detail/demangling/demangle_symbol.hpp
@@ -11,9 +11,11 @@
 #include <boost/dll/config.hpp>
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <string>
 #include <algorithm>
 #include <memory>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 #if defined(_MSC_VER) // MSVC, Clang-cl, and ICC on Windows

diff --git a/include/boost/dll/detail/demangling/itanium.hpp b/include/boost/dll/detail/demangling/itanium.hpp
@@ -8,9 +8,11 @@
 #define BOOST_DLL_DETAIL_DEMANGLING_ITANIUM_HPP_
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <algorithm>
 #include <iterator>
 #include <type_traits>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 #include <boost/dll/detail/demangling/mangled_storage_base.hpp>

diff --git a/include/boost/dll/detail/demangling/mangled_storage_base.hpp b/include/boost/dll/detail/demangling/mangled_storage_base.hpp
@@ -10,10 +10,12 @@
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
 #include <boost/type_index/ctti_type_index.hpp>
 
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <vector>
 #include <string>
 #include <map>
 #include <type_traits>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 #include <boost/dll/detail/demangling/demangle_symbol.hpp>

diff --git a/include/boost/dll/detail/demangling/msvc.hpp b/include/boost/dll/detail/demangling/msvc.hpp
@@ -10,9 +10,11 @@
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
 #include <boost/core/detail/string_view.hpp>
 
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <iterator>
 #include <algorithm>
 #include <type_traits>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 #include <boost/dll/detail/demangling/mangled_storage_base.hpp>

diff --git a/include/boost/dll/detail/elf_info.hpp b/include/boost/dll/detail/elf_info.hpp
@@ -17,10 +17,12 @@
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
 #include <boost/throw_exception.hpp>
 
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <cstdint>
 #include <cstring>
 #include <fstream>
 #include <vector>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 namespace boost { namespace dll { namespace detail {

diff --git a/include/boost/dll/detail/import_mangled_helpers.hpp b/include/boost/dll/detail/import_mangled_helpers.hpp
@@ -13,7 +13,9 @@
 #endif
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <type_traits>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 namespace boost { namespace dll { namespace experimental { namespace detail {

diff --git a/include/boost/dll/detail/macho_info.hpp b/include/boost/dll/detail/macho_info.hpp
@@ -15,11 +15,13 @@
 #endif
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <algorithm>
 #include <cstdint>
 #include <fstream>
 #include <string> // for std::getline
 #include <vector>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 namespace boost { namespace dll { namespace detail {

diff --git a/include/boost/dll/detail/pe_info.hpp b/include/boost/dll/detail/pe_info.hpp
@@ -15,11 +15,13 @@
 #endif
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <cstdint>
 #include <cstring>
 #include <fstream>
 #include <string> // for std::getline
 #include <vector>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 namespace boost { namespace dll { namespace detail {

diff --git a/include/boost/dll/detail/posix/path_from_handle.hpp b/include/boost/dll/detail/posix/path_from_handle.hpp
@@ -26,7 +26,9 @@
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
 #   include <mach-o/dyld.h>
 #   include <mach-o/nlist.h>
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #   include <cstddef> // for std::ptrdiff_t
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 namespace boost { namespace dll { namespace detail {

diff --git a/include/boost/dll/detail/posix/program_location_impl.hpp b/include/boost/dll/detail/posix/program_location_impl.hpp
@@ -23,7 +23,9 @@
 #if BOOST_OS_MACOS || BOOST_OS_IOS
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <string>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #include <mach-o/dyld.h>
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
@@ -51,7 +53,9 @@ namespace boost { namespace dll { namespace detail {
 #elif BOOST_OS_SOLARIS
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <stdlib.h>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 namespace boost { namespace dll { namespace detail {
@@ -65,10 +69,12 @@ namespace boost { namespace dll { namespace detail {
 #elif BOOST_OS_BSD_FREE
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <string>
+#include <stdlib.h>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #include <sys/types.h>
 #include <sys/sysctl.h>
-#include <stdlib.h>
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 namespace boost { namespace dll { namespace detail {
@@ -133,8 +139,10 @@ namespace boost { namespace dll { namespace detail {
 #elif BOOST_OS_QNX
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <fstream>
 #include <string> // for std::getline
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 namespace boost { namespace dll { namespace detail {

diff --git a/include/boost/dll/detail/posix/shared_library_impl.hpp b/include/boost/dll/detail/posix/shared_library_impl.hpp
@@ -18,10 +18,12 @@
 #include <boost/core/invoke_swap.hpp>
 #include <boost/predef/os.h>
 
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <utility>  // std::move
+#include <cstring> // strncmp
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 
 #include <dlfcn.h>
-#include <cstring> // strncmp
 #if !BOOST_OS_MACOS && !BOOST_OS_IOS && !BOOST_OS_QNX && !BOOST_OS_CYGWIN
 #   include <link.h>
 #elif BOOST_OS_QNX

diff --git a/include/boost/dll/detail/system_error.hpp b/include/boost/dll/detail/system_error.hpp
@@ -26,7 +26,9 @@
 #   include <dlfcn.h>
 #endif
 
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <system_error>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 

diff --git a/include/boost/dll/detail/type_info.hpp b/include/boost/dll/detail/type_info.hpp
@@ -16,8 +16,10 @@
 #  include <boost/winapi/basic_types.hpp>
 # endif
 
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <typeinfo>
 #include <cstring>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 namespace boost { namespace dll { namespace detail {

diff --git a/include/boost/dll/detail/windows/shared_library_impl.hpp b/include/boost/dll/detail/windows/shared_library_impl.hpp
@@ -10,16 +10,19 @@
 
 #include <boost/dll/config.hpp>
 
-#ifdef BOOST_HAS_PRAGMA_ONCE
-# pragma once
-#endif
+#include <boost/dll/shared_library_load_mode.hpp>
+#include <boost/dll/detail/aggressive_ptr_cast.hpp>
+#include <boost/dll/detail/system_error.hpp>
+#include <boost/dll/detail/windows/path_from_handle.hpp>
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
 #include <boost/core/invoke_swap.hpp>
 
 #include <boost/winapi/dll.hpp>
 
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <utility>  // std::move
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 #include <boost/dll/shared_library_load_mode.hpp>

diff --git a/include/boost/dll/import.hpp b/include/boost/dll/import.hpp
@@ -22,8 +22,10 @@
 #endif
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <memory>  // std::addressof
 #include <type_traits>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 #include <boost/dll/config.hpp>

diff --git a/include/boost/dll/import_class.hpp b/include/boost/dll/import_class.hpp
@@ -23,8 +23,10 @@
 #endif
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <memory>
 #include <utility>  // std::move
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 #include <boost/dll/smart_library.hpp>

diff --git a/include/boost/dll/import_mangled.hpp b/include/boost/dll/import_mangled.hpp
@@ -28,11 +28,12 @@
 #endif
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <memory>  // std::addressof
 #include <type_traits>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
-#include <boost/dll/config.hpp>
 #include <boost/dll/smart_library.hpp>
 #include <boost/dll/detail/import_mangled_helpers.hpp>
 

diff --git a/include/boost/dll/library_info.hpp b/include/boost/dll/library_info.hpp
@@ -29,8 +29,10 @@
 #include <boost/predef/architecture.h>
 #include <boost/throw_exception.hpp>
 
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <fstream>
 #include <type_traits>
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 #include <boost/dll/detail/pe_info.hpp>

diff --git a/include/boost/dll/runtime_symbol_info.hpp b/include/boost/dll/runtime_symbol_info.hpp
@@ -25,7 +25,9 @@
 #include <boost/predef/os.h>
 #include <boost/predef/compiler/visualc.h>
 
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <memory>  // std::addressof
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 #if BOOST_OS_WINDOWS

diff --git a/include/boost/dll/shared_library.hpp b/include/boost/dll/shared_library.hpp
@@ -27,8 +27,10 @@
 #include <boost/core/enable_if.hpp>
 #include <boost/core/explicit_operator_bool.hpp>
 
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <type_traits>
 #include <utility>  // std::move
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 #include <boost/dll/detail/system_error.hpp>

diff --git a/include/boost/dll/smart_library.hpp b/include/boost/dll/smart_library.hpp
@@ -25,8 +25,10 @@
 #include <boost/dll/config.hpp>
 
 #if !defined(BOOST_DLL_INTERFACE_UNIT)
+#if !defined(BOOST_DLL_USE_STD_MODULE)
 #include <type_traits>
 #include <utility>  // std::move
+#endif // !defined(BOOST_DLL_USE_STD_MODULE)
 #endif // !defined(BOOST_DLL_INTERFACE_UNIT)
 
 #if (__cplusplus < 201103L) && (!defined(_MSVC_LANG) || _MSVC_LANG < 201103L)